The present invention concerns internal combustion engines and particularly an engine wherein the compression ratio may be varied during operation to best adapt the engine to load conditions.
In the prior patent art are numerous Scotch yoke type engine disclosures which by their nature include opposed cylinders, pistons affixed to a common yoke with rectilinear yoke motion being translated into rotary motion by an offset crankpin of a crankshaft. For one or more reasons, yoke type internal combustion engines have not been adopted by the automotive industry. Further, such engines disclosed in the prior patent art, to the best of my knowledge, have no capability for altering piston stroke during engine operation.
Prior patent art includes U.S. Pat. No. 4,270,495 which discloses an engine capable of different piston stroke lengths and compression ratios. The engine has a pair of parallel cylinders arranged in side-by-side fashion and relies on an adjustable crankshaft mechanism positionable toward or away from the cylinders to effect stroke and compression changes. U.S. Pat. No. 4,112,826 shows a similar engine.
U.S. Pat. No. 4,182,288 is of interest as it discloses an engine with an adjustable compression chamber using an auxiliary cylinder and positionable piston therein with the chamber in communication with an engine cylinder. The volume of the auxiliary cylinder is variable to vary the total combustion chamber of a cylinder. The patent is additionally of interest in that it discloses means for altering phase relationships between driving and driven shafts.
U.S. Pat. No. 3,861,239 discloses the concept of a connecting rod coupled to a crankshaft by an eccentric bearing which rotates during engine operation to alter the piston stroke. U.S. Pat. No. 4,319,498 shows similar engine structure.
Other crankshaft-connecting rod disclosures are directed toward elliptical crankpin travel about a crankshaft axis to vary piston dwell at top dead center as shown in U.S. Pat. No. 1,873,908.